R help - Apr 2009 - Using as.formula() with the reshape package cast

I am trying to use the "cast" function from the reshape package, where
the
formula is not passed in directly, but as the result of the as.formula() 
function. 

Using reshape v. 0.7.2 

I am able to properly melt() by data with: 
> molten <- melt(x, id=1:2) 
then I can properly cast with this: 
> cast(molten, days ~ variable) 
but if I try 
> cast(molten, as.function("days ~ variable")) 
if returns the error: 

Error in check_formula(formula, varnames) : 
        Formula contains variables not in list of known variables 

I am not sure if the problem is with cast or as.formula() 

I did confirm that: 
> x <- days ~ variable 
> y <- as.formula("days ~ variable") 
> x==y 
TRUE


	[[alternative HTML version deleted]]

On Tue, Apr 7, 2009 at 8:44 AM,  <ryan.sheftel at malbecpartners.com>
wrote:
>
> I am trying to use the "cast" function from the reshape package,
where the
> formula is not passed in directly, but as the result of the as.formula()
> function.
>
> Using reshape v. 0.7.2
>
> I am able to properly melt() by data with:
>
>> molten <- melt(x, id=1:2)
>
> then I can properly cast with this:
>
>> cast(molten, days ~ variable)
>
> but if I try
>
>> cast(molten, as.function("days ~ variable"))
You're calling as.function ;)  Also, I think you should be able to
pass the string directly - reshape will convert it to a formula for
you.

Hadley


-- 
http://had.co.nz/

On Tue, 2009-04-07 at 09:47 -0400, ryan.sheftel at malbecpartners.com
wrote:
> I am trying to use the "cast" function from the reshape package,
where the
> formula is not passed in directly, but as the result of the as.formula() 
> function. 
> 
> Using reshape v. 0.7.2 
> 
> I am able to properly melt() by data with: 
> 
> > molten <- melt(x, id=1:2) 
> 
> then I can properly cast with this: 
> 
> > cast(molten, days ~ variable) 
> 
> but if I try 
> 
> > cast(molten, as.function("days ~ variable")) 
                    ^^^^^^^^^

Did you really use as.function not as.formula as you claim or is this a
typo in composing this posting? If this is what you typed, that may well
be the source of the error.

HTH

G
> 
> if returns the error: 
> 
> Error in check_formula(formula, varnames) : 
>         Formula contains variables not in list of known variables 
> 
> I am not sure if the problem is with cast or as.formula() 
> 
> I did confirm that: 
> 
> > x <- days ~ variable 
> 
> > y <- as.formula("days ~ variable") 
> 
> > x==y 
> TRUE
> 
> 
> 	[[alternative HTML version deleted]]
> 
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